1. Field of the Invention
The present invention relates to a laminated composite and a method of producing the same, which composite is composed of a layer of fiber-reinforced ceramics and a layer of SiC ceramics and is applicable to various mechanical parts which require high heat resistance, particularly high strength and high toughness in high temperature.
2. Description of the Prior Art
A variety of ceramics have been hitherto proposed for a material of various mechanical parts which are to be exposed to high temperature. Those ceramics are considered to be a suitable material for mechanical parts, for example, for parts of a gas turbine. However, the mechanical parts of the gas turbine require high strength and high toughness in high temperature in particular.
Thus, some ceramics which are proposed to be used for the gas turbine, when exposed to combustion gas having a high temperature, tend to be broken because they can not withstand tensile stress. For example, monolithic ceramics, when they have a tiny defective part having a length ranging from tens of micron to hundreds of micron, tend to be easily broken by tensile stress due to their low fracture toughness. When monolithic ceramics are so made as to increase their fracture toughness, that is, to increase their plastic deformation capability at an end of a crack formed therein, other mechanical characteristics of them will be deteriorated due to inevitable increase of creep speed. Therefore, monolithic ceramics are limited in improving their fracture toughness. Furthermore, when monolithic ceramics are constructed to have more than a certain size, the strength of the same will be lowered drastically.
In view of the above, ceramic composites have been proposed to compensate for unsatisfactory fracture toughness of monolithic ceramics. For example, ceramic composites which are reinforced by acicular particles such as whisker or platelike particles and the like have somewhat improved fracture toughness as compared with that of monolithic ceramics. However, production of those ceramic composites is too complicated for carrying out an economical production thereof. Continuous-fiber reinforced ceramic composites have high fracture toughnes thereby making them hard to break catastrophically. However, those composites are relatively weak against shearing stress.